http://gra103.aca.ntu.edu.tw/gra2007/gra/wu/104%E5%AD%B8%E5%B9%B4%E7%AC%AC1%E5%AD%B8%E6%9C%9F%E7%A2%A9%E5%A3%AB%E9%80%95%E4%BF%AE%E5%8D%9A%E5%A3%AB%E5%90%8D%E5%96%AE.pdf